Image processing apparatus and method, and storage medium therefor

ABSTRACT

In an image processing apparatus, an input image is synthesized with a stored image supplied from a storage unit and having been shifted so that the positions of the pixels in the image areas of the input image and of the stored image, associated with a telop, will coincide. The level distribution of the pixel values of the input image is maintained in the telop.

This is a continuation of application Ser. No. 09/887,635, filed Jun.22, 2001, the entirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to image processing. Moreparticularly, the present invention relates to an image processingapparatus and method, and a storage medium therefor for extracting aspecific area of an image.

2. Description of the Related Art

Conventionally, methods have been proposed for extracting a specificportion of an image based on the features of the specific portion.

For example, a telop (video caption) can be extracted from an imagebased on its features that the luminance level thereof is higher and theedge thereof is sharper compared with the background portion.

However, there has existed the problem that the telop cannot beprecisely extracted if part of the background portion is similar to thetelop with respect to the luminance level and the sharpness of the edge.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above, and an objectthereof is to provide an image processing apparatus and method, andstorage medium therefor, which allows a specific area such as a telop tobe extracted more precisely.

To this end, the present invention, in one aspect thereof, provides adigital image signal processing apparatus, to which an input digitalimage signal is input. The digital image processing apparatus includes astoring unit for storing a digital image signal; an extracting unit forextracting a signal representing a specific area from the digital imagesignal stored in the storing unit; a detecting unit for detecting amotion of the specific area based on the input digital image signal andthe extracted signal representing the specific area; and a synthesizingunit for synthesizing the input digital image signal and the extractedsignal representing the specific area so as to align the position of theextracted specific area and the position of a corresponding arearepresented by the input digital image signal; wherein the storing unitupdates the digital image signal stored therein with an output signalsupplied from the synthesizing unit.

The synthesizing unit preferably includes a shifting unit for shiftingthe position of the input image or the position of the specific areaaccording to the motion detected by the detecting unit; and an addingunit for adding the input image and the specific area.

In the signal processing apparatus, preferably, an object constitutingthe specific area moves differently from an object constituting theother area.

The detecting unit may detect the motion on the basis of a unit having apitch smaller than that of the pixels of the input image, the pixeldensity of the synthesized image being higher than the pixel density ofthe input image.

Alternatively, the detecting unit may detect the motion on the basis ofa unit having the same pitch as that of the pixels of the input image,the pixel density of the synthesized image being the same as the pixeldensity of the input image.

The synthesizing unit may include a shifting unit for shifting theposition of the specific area according to the motion detected by thedetecting unit; and an adding unit for adding the specific area havingbeen shifted and the input image.

Alternatively, the synthesizing unit may include a shifting unit forshifting the position of the input image according to the motiondetected by the detecting unit; and an adding unit for adding the inputimage having been shifted and the specific area.

The signal processing apparatus may further include a second extractingunit for extracting an area corresponding to the specific area from theinput image.

The adding unit may add the input image and the specific area by aweighted addition.

The present invention, in another aspect thereof, provides a method ofprocessing an input digital image signal. The method includes the stepsof storing a digital image signal; extracting a signal representing aspecific area from the digital image signal stored; detecting a motionof the specific area based on the input digital image signal and theextracted signal representing the specific area; synthesizing the inputdigital image signal and the extracted signal representing the specificarea so as to align the position of the extracted specific area and theposition of a corresponding area represented by the input digital imagesignal; and updating the digital image signal stored with a signalobtained in the synthesizing step.

The synthesizing step preferably includes the steps of shifting theposition of the input image or the position of the specific areaaccording to the motion detected in the detecting step; and adding theinput image and the specific area.

In the method, preferably, an object constituting the specific areamoves differently from an object constituting the other area.

The detecting step may detect the motion on the basis of a unit having apitch smaller than that of the pixels of the input image, the pixeldensity of the synthesized image being higher than the pixel density ofthe input image.

Alternatively, the detecting step detects the motion on the basis of aunit having the same pitch as that of the pixels of the input image, thepixel density of the synthesized image being the same as the pixeldensity of the input image.

The synthesizing step may include the steps of shifting the position ofthe specific area according to the motion detected in the detectingstep; and adding the specific area having been shifted and the inputimage.

Alternatively, the synthesizing step may include the steps of shiftingthe position of the input image according to the motion detected in thedetecting step; and adding the input image having been shifted and thespecific area.

The method may further include a second extracting step of extracting anarea corresponding to the specific area from the input image.

The adding step may add the input image and the specific area by aweighted addition.

The present invention, in its still another aspect thereof, provides acomputer-readable storage medium storing a program for processing aninput digital image signal. The program includes the steps of storing adigital image signal; extracting a signal representing a specific areafrom the digital image signal stored; detecting a motion of the specificarea based on the input digital image signal and the extracted signalrepresenting the specific area; synthesizing the input digital imagesignal and the extracted signal representing the specific area so as toalign the position of the extracted specific area and the position of acorresponding area represented by the input digital image signal; andupdating the digital image signal stored with a signal obtained in thesynthesizing step.

The synthesizing step preferably includes the steps of shifting theposition of the input image or the position of the specific areaaccording to the motion detected in the detecting step; and adding theinput image and the specific area.

In the method, preferably, an object constituting the specific areamoves differently from an object constituting the other area.

The detecting step may detect the motion on the basis of a unit having apitch smaller than that of the pixels of the input image, the pixeldensity of the synthesized image being higher than the pixel density ofthe input image.

Alternatively, the detecting step detects the motion on the basis of aunit having the same pitch as that of the pixels of the input image, thepixel density of the synthesized image being the same as the pixeldensity of the input image.

The synthesizing step may include the steps of shifting the position ofthe specific area according to the motion detected in the detectingstep; and adding the specific area having been shifted and the inputimage.

Alternatively, the synthesizing step may include the steps of shiftingthe position of the input image according to the motion detected in thedetecting step; and adding the input image having been shifted and thespecific area.

The method may further include a second extracting step of extracting anarea corresponding to the specific area from the input image.

The adding step may add the input image and the specific area by aweighted addition.

In accordance with the image processing apparatus and method, and thestorage medium storing the program therefor, an image is stored, aspecific area having specific features is extracted from the imagestored, a motion of the specific area is detected based on the specificarea extracted and an input image, and the specific area and the inputimage are synthesized in alignment. Accordingly, the specific area canbe extracted precisely.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an image processing apparatus according toan embodiment of the present invention;

FIG. 2 is a block diagram of an extracting circuit in the imageprocessing apparatus shown in FIG. 1;

FIG. 3 is a flowchart showing the operation of the image processingapparatus shown in FIG. 1;

FIG. 4 is a diagram for explaining the operations of a position shiftingcircuit and a synthesizing circuit in the image processing apparatusshown in FIG. 1;

FIG. 5 is another diagram for explaining the operations of the positionshifting circuit and the synthesizing circuit in the image processingapparatus shown in FIG. 1;

FIG. 6 is yet another diagram for explaining the operations of theposition shifting circuit and the synthesizing circuit in the imageprocessing apparatus shown in FIG. 1;

FIG. 7 is a diagram for explaining the operation of a motion vectordetecting circuit in the image processing apparatus shown in FIG. 1;

FIGS. 8A and 8B are diagrams illustrating a basic block and a referenceblock, respectively;

FIG. 9 is a diagram showing the movement of the reference block shown inFIG. 8B;

FIGS. 10A and 10B are diagrams showing examples of tables used fordetecting a motion vector;

FIG. 11 is a block diagram of an image processing apparatus according toanother embodiment of the present invention;

FIG. 12 is a flowchart showing the operation of the image processingapparatus shown in FIG. 11;

FIG. 13 is a block diagram of an image processing apparatus according toyet another embodiment of the present invention;

FIG. 14 is a flowchart showing the operation of the image processingapparatus shown in FIG. 13; and

FIG. 15 is a block diagram of an example of a computer for implementingthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram of an image processing apparatus according toan embodiment of the present invention. The image processing apparatusallows extraction of an image area (hereinafter referred to as aspecific area) such as a telop, characterized by the motion thereofbeing different from that of the background area.

An image which is input to the image processing apparatus is fed to adelaying circuit 11 and a motion vector detecting circuit 15. Thedelaying circuit 11 delays the input image for an amount of timerequired for the processing in a synthesizing circuit 12 through aposition shifting circuit 16, to be described later, and supplies theimage to the synthesizing circuit 12 with the delay, so that thesynthesizing circuit 12 synthesizes the input image and an imagecorresponding thereto, as will be described later.

The synthesizing circuit 12 synthesizes the input image supplied fromthe delaying circuit 11 and an image supplied from the position shiftingcircuit 16, and supplies the synthesized image to a storage unit 13.

The storage unit 13 stores the image supplied from the synthesizingcircuit 12, and supplies the stored image to an extracting circuit 14and the position shifting circuit 16.

The extracting circuit 14 extracts a specific area (more precisely, animage area which has been determined as the specific area), and suppliesthe image data of the extracted image area and information regarding thedisplay position thereof to the motion vector detecting circuit 15 andan external apparatus (not shown).

The motion vector detecting circuit 15 receives the input image and alsoreceives, from the extracting circuit 14, the image data of the imagearea determined as the specific area of the stored image and informationregarding the display position thereof. Using the image data and thedisplay position information supplied from the extracting circuit 14,the motion vector detecting circuit 15 detects the motion vector betweenthe specific area of the stored image (the image area determined as thespecific area of the stored image) and an image area of the input image,corresponding to the specific area, and outputs the result to theposition shifting circuit 16.

The position shifting circuit 16 shifts the position of the stored imagesupplied from the storage unit 13 based on the motion vector suppliedfrom the motion vector detecting circuit 15, and supplies the shiftedimage to the synthesizing circuit 12.

FIG. 2 is a block diagram of an example of the extracting circuit 14,which is arranged so as to extract a telop as the specific area.

The stored image from the storage unit 13 is supplied to an edgedetecting circuit 31, a level detecting circuit 32, and a telopdetecting circuit 33.

The edge detecting circuit 31 detects the sharpness of the edge (edgedetecting process) for each predetermined image area of the storedimage, and supplies the results to the telop detecting circuit 33.

The level detecting circuit 32 detects the luminance level for eachpredetermined image area of the stored image (corresponding to each ofthe image areas for which the edge detecting process is performed in theedge detecting circuit 31), and supplies the results to the telopdetecting circuit 33.

The telop detecting circuit 33 compares the sharpness of the edgedetected by the edge detecting circuit 31 and the luminance leveldetected by the level detecting circuit 32 against predeterminedthreshold values for each of the image areas. If the sharpness of theedge and the luminance level of an image area are both higher than theirrespective threshold values, the image area of the stored image isdetermined as a telop. The telop can be detected in this manner becauseit usually has a sharp edge and a high luminance level.

The telop detecting circuit 33 obtains the image data and the displayposition information of the image area determined as the telop from thestored image, and outputs the image data and the display positioninformation to the motion vector detecting circuit 15 and the externalapparatus (not shown).

Although the extracting circuit 14 has been described in relation to aspecific construction for extracting a telop, the extracting circuit 14is not limited thereto, and may be implemented in differentconstructions which allow the extraction of a specific area.

Next, the operation of the image processing apparatus will be describedwith reference to the flowchart shown in FIG. 3, in relation to anexample in which a telop is extracted as the specific area.

In step S1, the motion vector detecting circuit 15 detects the motionvector between an image area of the stored image, determined as a telopand extracted by the extracting circuit 14, and the corresponding imagearea of an input image (hereinafter referred to as field A), andsupplies the result to the position shifting circuit 16.

It is to be assumed herein that the image input has already been startedand an image has thus been stored in the storage unit 13. When the imagedata of the new input image (the field A) is input, the extractingcircuit 14 obtains the image data and the display position informationof the image area determined as the telop from the image stored in thestorage unit 13, according to the method described earlier withreference to FIG. 2. The extracting circuit 14 then supplies the imagedata and the display position information to the motion vector detectingcircuit 15.

Next, in step S2, the position shifting circuit 16 shifts the positionof the stored image before the synthesis supplied from the storage unit13 based on the motion vector supplied from the motion vector detectingcircuit 15, so that the positions of the pixels in the image area of thestored image before the synthesis, determined as the telop, and thepositions of the pixels in the corresponding image area of the field Awill coincide, as shown in (A) of FIG. 4.

The positions of the pixels in the other image areas (e.g. thebackground) of the stored image, not associated with the telop, will notcoincide with the positions of the pixels in the corresponding imagearea of the field A, for example, as shown in (A) of FIG. 5.

The position shifting circuit 16 supplies the shifted image to thesynthesizing circuit 12.

In step S3, the synthesizing circuit 12 synthesizes the field A suppliedfrom the delaying circuit 11 and the stored image having been shifted bythe position shifting circuit 16 according to the following formula, andsupplies the synthesized image to the storage unit 13.Synthesized value=(pixel value of the input image×N+pixel value of thestored image×M)/(N+M),

where N and M are predetermined coefficients.

That is, the input image and the stored image are weight-added on apixel-by-pixel basis, the synthesized value serving as the pixel valueof the image to be supplied to the storage unit 13.

In the example shown in FIGS. 4 and 5, the input image and the storedimage are synthesized with the positions of the pixels in the image areaof the stored image, determined as the telop (i.e., the specific area),and the positions of the pixels in the corresponding image area on thefield A in alignment, as shown in (A) of FIG. 4, while the positions ofthe pixels in the image area of the stored image, not associated withthe telop, and the positions of the pixels in the corresponding imagearea on the field A out of alignment, as shown in (A) of FIG. 5.

The storage unit 13 updates the stored image with the synthesized imagesupplied from the synthesizing circuit 12.

Then, in step S4, the extracting circuit 14 reads the updated storedimage from the storage unit 13. In step S5, the extracting circuit 14extracts an image area determined as a telop, and outputs the extractedportion to the motion vector detecting circuit 15 and the externalapparatus (not shown). Then, the processing returns to step S1, and theprocessing steps are repeated.

As described above, the input image and the stored image are synthesizedso that the positions of the pixels in the image area of the storedimage, determined as the telop (i.e., the specific area), will coincidewith the positions of the pixels in the corresponding image area of thefield A (input image), as shown in (A) of FIG. 4. Thus, the leveldistribution of the telop on the stored image is maintained even afterthe synthesis, as shown in (B) of FIG. 4. Meanwhile, the positions ofthe pixels in the image areas of the input image and the stored image,not associated with the telop, do not coincide, as shown in (A) of FIG.5. Thus, after the synthesis, the level distribution in the image areaof the stored image, not associated with the telop, will be flattened,as shown in (B) of FIG. 5.

As a result, the sharpness of the edge and the luminance level of thetelop become even higher compared with the other image area, allowingthe extracting circuit 14 to extract the telop more precisely.

The description has been made hereinabove in relation to an example inwhich the input image and the stored image are synthesized so that thepositions of the pixels of the input image and of the stored image,associated with the telop, will coincide. Alternatively, the input imageand the stored image may be synthesized so that the positions of thepixels of the input image and the stored image have a predetermineddifference, as shown in (A) of FIG. 6. In this case, the density of thepixels in the telop is increased, as shown in (B) of FIG. 6. Meanwhile,the pixel values in the image area not associated with the telop areflattened similarly as in the example described earlier, allowing aprecise extraction of the telop.

In this example, the density of the pixels of the specific area isincreased, and is thus different from the density of the pixels in theinput image. For this reason, the motion vector detecting circuit 15detects the motion vector by the method described below.

The description will be made in relation to an example in which themotion vector is detected between an image Pa (corresponding to theinput image) shown in (A) of FIG. 7 and an image Pb (corresponding tothe specific area) having a density higher (four times higher in thevertical direction) than that of the image Pa. In FIG. 7, solid linesare what is referred to as lines, on which pixels (not shown) aredisposed, whereas pixels are not provided on dotted lines equallydividing each of the spaces between the solid lines into four.

First, the high-density image Pb ((C) of FIG. 7) is divided into fourimages; namely, an image Pb1 in which the positions of the linescoincide relative to the image Pa, an image Pb2 in which the positionsof the lines are shifted downward by one line relative to the image Pb1,an image Pb3 in which the positions of the lines are shifted downward byone line relative to the image Pb2, and an image Pb4 in which thepositions of the lines are shifted downward by one line relative to theimage Pb3, as shown in (B) of FIG. 7.

Next, a basic block Ba (5×5), shown in FIG. 8A, is set at apredetermined position of the image Pa (e.g., the position correspondingto the display position of the specific area). Also, a reference blockBb, shown in FIG. 8B, having the same size and shape as the basic blockBa, is set on one of the images Pb1 to Pb4, for example, the image Pb1,at a position (hereinafter referred to as the basic position)corresponding to the position of the basic block Ba set on the image Pa.

Then, the differences (absolute values) between the pixel values of theimage Pa within the basic block Ba and the pixels values of the imagePb1 within the reference block Bb set at the basic position arecalculated, and the sum of the absolute values (total value) iscalculated. The reference block Bb is moved horizontally and verticallypixel by pixel on the image Pb1 with the standard position as thecenter, and at each of the positions, the sum of the differences betweenthe pixel values of the image Pb1 within the reference block Bb and thepixel values of the image Pa within the reference block Pa iscalculated. Then, a table, in which the sums of the absolute values arestored at the positions respectively corresponding to the positions ofthe reference block Bb, is generated.

For example, if the reference block Bb is moved for two pixels rightwardand leftward and for one pixel upward and downward relative to the basicposition, 5×3 sums of the absolute values are calculated, a table T1shown in FIG. 10A thus being generated. For example, the sum X0 of theabsolute values in the table T1 is calculated when the reference blockBb is set at the basic position (corresponding to the basic block Ba).That is, the sum X0 of the absolute value is stored at the positioncorresponding to the center pixel of the basic block Ba.

As described above, the reference block Bb is set on the image Pb1 andthe table T1 is generated, and then the reference block Bb is set oneach of the images Pb2 to Pb4 and the corresponding tables T2 to T4 aregenerated in a similar manner.

The table T2 stores the sums of the absolute values calculated when thereference block Bb is set on the image Pb2, corresponding to thepositions one line lower relative to the positions of the sums of theabsolute values stored in the table T1.

The table T3 stores the sums of the absolute values calculated when thereference block Bb is set on the image Pb3, corresponding to thepositions one line lower relative to the positions of the sums of theabsolute values stored in the table T2. The table T4 stores the sums ofthe absolute values calculated when the reference block Bb is set on theimage Pb4, corresponding to the positions one line lower relative to thepositions of the sums of the absolute values stored in the table T3.

Then, the tables T1 to T4 thus generated are combined to generate atable T0 shown in FIG. 10B. That is, the table T0 stores 5×3×4 sums ofthe absolute values.

Then, the minimum value among the sums of the absolute valuesconstituting the table T0 is detected, and the reference block Bbassociated with the minimum value is detected. Then, the vector betweenthe center pixel of the basic block Ba (i.e., the center pixel of theimage Pa) and the center pixel of the reference block Bb (i.e., thecenter pixel of one of the images Pb1 to Pb4) is detected as the motionvector.

Even if the densities of pixels in the images differ, the motion vectorcan be detected in the above-described manner. The method is disclosedin Japanese Unexamined Patent Application Publication No. 2000-236554A.

In the image processing apparatus shown in FIG. 1, the position of thestored image is shifted; alternatively, the arrangement may be such thatthe position of the input image is shifted. FIG. 11 is a block diagramof an image processing apparatus according to another embodiment of thepresent invention, in which the position of the input image is shifted.

In the image processing apparatus shown in FIG. 11, the input image issupplied to the motion vector detecting circuit 15 and also to theposition shifting circuit 16. The storage unit 13 supplies the storedimage to the synthesizing circuit 12.

The operation of the image processing apparatus shown in FIG. 11 will bedescribed with reference to the flowchart shown in FIG. 12. Again, thedescription will be made in relation to an example in which a telop isextracted as a specific area.

In step S11, the motion vector detecting circuit 15 detects the motionvector between the image area of the stored image, determined as thetelop and extracted by the extracting circuit 14, and the correspondingimage area of the input image, and supplies the result to the positionshifting circuit 16.

In step S12, the position shifting circuit 12 shifts the position of theinput image based on the motion vector supplied from the motion vectordetecting circuit 15 so that the positions of the pixels in the imagearea of the stored image, determined as the telop, and the positions ofthe pixels in the corresponding image area of the input image will be inalignment, as shown in (A) of FIG. 4, while the positions of the pixelsin the image area (e.g., the background area) of the stored image, notdetermined as the telop, and the positions of the pixels in thecorresponding image area of the input image will be out of alignment, asshown in (A) of FIG. 5.

In step S13, the synthesizing circuit 12 synthesizes the input imagehaving been shifted by the position shifting circuit 16 and the storedimage supplied from the storage unit 13, and supplies the synthesizedimage to the storage unit 13. The storage unit 13 updates the storedimage with the synthesized image supplied from the synthesizing circuit12.

In steps S14 and S15, the same processes as in steps S4 and S5 shown inFIG. 3 are executed, and the descriptions thereof will be omitted.

In this embodiment as well, the stored image is supplied to theextracting circuit 14 with the level distribution of the pixel values inthe specific area maintained or the density of the pixels increased, andwith the pixels values of the background area, etc. flattened. Thus, theextracting circuit 14 is allowed to extract the specific area precisely.

In the image processing apparatus shown in FIG. 1, only the singleextracting circuit 14 is provided subsequent to the storage unit 13;alternatively, another extracting circuit 21 may be provided instead ofthe delaying circuit 11. FIG. 13 is a block diagram of an imageprocessing apparatus according to yet another embodiment of the presentinvention.

The extracting circuit 21 is constructed identically to the extractingcircuit 14, and it extracts an image area determined as a telop from aninput image, and supplies the extracted image area to the synthesizingcircuit 12.

The operation of the image processing apparatus shown in FIG. 13 will bedescribed with reference to the flowchart in FIG. 14.

In step S21, the same process as in step S1 shown in FIG. 3 is executed,and the description thereof will be omitted.

In step S22, the position shifting circuit 16 shifts the position of thestored image based on the motion vector supplied from the motion vectordetecting circuit 15 so that the positions of the pixels in the imagearea of the stored image, determined as the telop and extracted by theextracting circuit 14, and the positions of the pixels in the image areaof the input image, determined as the telop and extracted by theextracting circuit 21, will be in alignment, as shown in (A) of FIG. 4.

In step S23, the synthesizing circuit 12 synthesizes the image area ofthe input image, determined as the telop and extracted by the extractingcircuit 21, and the stored image having been shifted by and suppliedfrom the position shifting circuit 16, and supplies the synthesizedimage to the storage unit 13. The storage unit updates the stored imagewith the synthesized image supplied from the synthesizing circuit 12.

In steps S24 and S25, the same processes as in steps S4 and S5 shown inFIG. 3 are executed, and the descriptions thereof will be omitted.

Although the embodiments have been described above in relation to theexamples in which a telop is extracted as a specific area, the presentinvention is not limited thereto, and an object which moves differentlyfrom the background area, for example, an image area of a movingautomobile or a moving person, may be extracted as the specific area.

The series of processes described above may be implemented in softwareas well as in hardware. When the series of processes is implemented insoftware, a program of the software is installed and executed on acomputer, whereby the functionality of any one of the image processingapparatuses described above is achieved.

FIG. 15 is a block diagram of a computer 101 which functions as any oneof the image processing apparatuses described above. Referring to FIG.15, an input/output interface 116 is connected to a CPU (CentralProcessing Unit) 111 via a bus 115. When a command from the user isinput from an input unit 118 including, for example, a keyboard, amouse, etc., via the input/output interface 116 to the CPU 111, the CPU111 loads a program stored in, for example, a ROM (Read-Only Memory)112, a hard disk 114, or a storage medium mounted on a drive 120, suchas a magnetic disk 131, an optical disk 132, a magneto-optical disk 133,and a semiconductor memory 134, whereby various processes, for example,the series of processes shown in the flowcharts of FIGS. 3, 12, and 14,are executed. Furthermore, the CPU 111 outputs, as required, the resultof the processes to an output unit 117 including, for example, an LCD(Liquid Crystal Display) via the input/output interface 116. The programmay be provided to the user integrally with the computer 101 by beingprestored on the hard disk 114 or the ROM 112, as a package media suchas the magnetic disk 131, the optical disk 132, the magneto-optical disk133, and the semiconductor memory 134, or to the hard disk 114 via acommunications unit 119 from a satellite, a network, etc.

In the program stored on the storage medium, the processing stepsdescribed hereinabove need not necessarily be executed sequentially inthe described order, and may be executed in parallel or individually.

1. A method of processing an input digital image signal, said method comprising the steps of: storing a digital image signal; extracting a signal representing a specific area from the digital image signal stored; detecting a motion of the specific area based on the input digital image signal and the extracted signal representing a specific area; synthesizing the input digital image signal and the digital image signal stored in said storing means so as to align a position of the extracted specific area and a position of a corresponding area represented by the input digital image signal; and updating the digital image signal stored with a signal obtained in the synthesizing step.
 2. A method according to claim 1, wherein the synthesizing step comprises the steps of: shifting the position of the input image or the position of the specific area according to the motion detected in the detecting step; and adding the input image and the specific area.
 3. A method according to claim 2, wherein the adding step adds the input image and the specific area by a weighted addition.
 4. A method according to claim 2, wherein the adding step adds the input image and the specific area by a weighted addition.
 5. A method according to claim 1, wherein an object constituting said specific area moves differently from an object constituting the other area.
 6. A method according to claim 1, wherein the detecting step detects the motion on the basis of a unit having a pitch smaller than that of the, pixels of the input image, the pixel density of the synthesized image being higher than the pixel density of the Input image.
 7. A method according to claim 1, wherein the detecting step detects the motion on the basis of a unit having the same pitch as that of the pixels of the input image, the pixel density of the synthesized image being the same as the pixel density of the input image.
 8. A method according to claim 1, wherein the synthesizing step comprises the steps of: shifting the position of the specific area according to the motion detected in the detecting step; and adding the specific area having been shifted and the input image.
 9. A method according to claim 8, wherein the adding step adds the input image and the specific area by a weighted addition.
 10. A method according to claim 1, wherein the synthesizing step comprises the steps of: shifting the position of the input image according to the motion detected in the detecting step; and adding the input image having been shifted and the specific area.
 11. A method according to claim 10, wherein the adding step adds the input image and the specific area by a weighted addition. 